The present invention relates to offshore jacket structures such as those for supporting drilling platforms and, in particular, to the flooding and grouting of pile sleeves for such structures during installation thereof on a seabed.
Offshore structures of the type utilized in the drilling of oil or gas wells generally comprise a jacket which is anchored to the seabed and a platform which is supported on the jacket above the water surface. The jacket may comprise a plurality of legs or main sleeves which rest on the seabed and project upwardly beyond the water surface to carry the platform. Pile members are driven through the main sleeves (and/or through skirt sleeves attached to the main sleeves) and into the seabed to pin the jacket to the seabed. Apparatus of this type is disclosed for example in U.S. Pat. No. 3,987,636 issued to Hruska et al on Oct. 26, 1976 and assigned to the assignee of this invention. The disclosure of that patent is incorporated herein by reference as if set forth at length.
Generally, the jacket is initially fabricated at a land-based facility and then towed on its side in a floating condition to an offshore work site. Thereafter, the jacket is turned to an upright position within the water by selectively flooding the lower ends of at least some of the water-engaging sleeves. This can be achieved by manually actuating a valve situated on the wall of the sleeve to communicate the interior of the sleeve with the surrounding water. After the jacket has been turned, other compartments are flooded, whereby the jacket sinks onto the seabed. Thereafter, the flood valves are closed and pile members are driven through the sleeves and into the seabed by suitable pile-driving equipment located at the water surface.
In order to permanently secure the piles in place, grouting is introduced into the annulus formed between the outer face of each pile and its associated leg or skirt sleeve. The grout is pumped downwardly from a source at the water surface, through a grout supply line, the end of which is connected to a grout valve, such as a check valve, at an inlet port in the sleeve wall. The grout supply line is usually connected to the sleeve and extends along the length thereof to the water surface. It will be appreciated that separate grout openings and separate flood valves as well as separate grout lines and flood valve manipulators have heretofore been required in each sleeve for flooding and grouting, adding to the fabricating cost of the jacket as well as to the manipulative efforts required.
It is, therefore, an object of the present invention to minimize or alleviate problems of the type discussed above.
Another object of the present invention is to simplify the equipment and operation required to flood and grout a jacket sleeve.
A further object of the invention is to reduce the number of inlets and valves required for each sleeve for flooding and grouting operations.
An additional object of the invention is to facilitate the manipulation of a subsea valve from the water surface.
Still another object of the invention is to unitize a grout conduit and valve manipulator on a jacket structure.
A further object of the invention is to enable flood water and grout to be introduced into a jacket sleeve through a common opening.
It is another object of the invention to provide a flood and grout valve which includes a housing having flood openings communicating with ambient water, a rotatable gate in the housing for opening and closing the flood openings, and a check valve for grout which is mounted on the gate and conducts grout to the interior of the gate.